Embodiments of the invention relate to semiconductor structures, in particular, for defect-free silicon-germanium (SiGe)-on-insulator fins formed on a bulk silicon (Si) substrate and a method of manufacturing the same.
SiGe Fin field-effect transistor (FinFET) semiconductor structures are a viable option for continued scaling of FinFET to 10 nm and beyond, however, there are two major issues with SiGe fin fabrication. SiGe fins formed by growing a SiGe layer on a bulk Si substrate is limited by the so-called critical thickness. When SiGe is grown on Si, beyond the critical thickness, dislocations start to generate in SiGe films, resulting in defective SiGe fins. Isolation of SiGe fin from the bulk Si is not trivial. N-type dopants (e.g., phosphorus or arsenic) are used for a punchthrough stopping region under SiGe fins to suppress source/drain punchthrough. Unfortunately, N-type dopants have a greater diffusion rate in SiGe than in Si, resulting in undesired encroachment of punchthrough Si (PTS) dopants into SiGe channel, resulting in degradation of device performance and increase of device variability.